I looked at the furrion system that goes with the pre-installed kit on our new trailer and the price is insane.
I previously installed a backup camera and aftermarket stereo in my truck so this option works for me.
My solution is going to be to mount another backup camera, probably under the bumper for now, and run the wires up to the trailer plug wires. The backup camera on my truck is just two connections near the license plate, the video and the power, so as part of my hook up process I'll just unplug the truck cam and plug in the trailer cam. I bought a back up cam with led lighting for $35 and spent another $12 on an extension cable to reach the truck. It won't be as nice as the high mounted furroin but until I figure out how to route the wires up to the top, this is my plan.
I have noticed the bottom is just corrugated plastic sheet that is screwed on, and easily accessed. I'm going to look and see if I can just drop the wires down to the bottom from the "observation" camera mount and then run them forward.